SQUALODONTS AND ZEUGLODONTS. 63 
Chinese White Another representative of this group is the Chinese white dolphin 
Dolphin. § = (8. sinensis), from Quemoy Island, in the harbour of Amoy, and the 
Foochow and Canton rivers. It is said to be characterised by its general milk- 
white colour, pinkish fins, and black eyes. 
Camerun The most interesting member of this group is, however, the 
Dolphin. yecently described Camerun dolphin (S. tewzsv) from the estuaries and 

THE PALE RIVER-DOLPHIN. 
(From True, Bulletin of the U.S. National Museum, 1889.) 
rivers of the Camerun district of Western Africa, which is reported to be of 
herbivorous habit. If this alleged habit should be confirmed, this dolphin will 
differ not only from all the other members of the family to which it belongs, but 
likewise from all other living Cetaceans. 
SQUALODONTS AND ZEUGLODONTS. 
Families SQUALODONTIDE and ZEUGLODONTIDZ. 
In addition to numerous extinct representatives of the existing Cetacean 
families, to some of which reference has been made above, there are two extinct 
groups which cannot be included in either of the existing families; one of these 
differing very much indeed from all modern Cetaceans. 
Pre neaetia The name of squalodonts (genus Squwalodov) is applied to the 
members of the first of these two groups on account of the somewhat 
shark-like structure of their cheek-teeth. In the general characters of their skulls 
these Cetaceans approximate to the modern dolphins, from which they are, however, 
at once distinguished by the teeth being of different characters in different parts 
of the jaws, as in ordinary mammals. They have a total of fifteen teeth on each 
side of both the upper and lower jaws. Of these the first four are of simple 
structure, and correspond to the incisors and canines of other mammals; the next 
four, which are also comparatively simple, appear to represent the premolars ; while 
the last seven have two roots, and laterally-compressed triangular crowns, with 
sharp cutting edges, upon which there are a number of cusps arranged in a saw- 
like manner. The squalodonts, which are found in Miocene and Pliocene forma- 
tions, both in the Old and New World, clearly form one step between modern 
Cetaceans and ordinary mammals. And, so far as the structure of their teeth can 
be relied upon, they appear to suggest a kinship between Cetaceans and Carnivores. 
